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be·hav·ior (bĭ-hāvyər)
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n.
1. The manner in which one acts or behaves.
2.
a. The actions or reactions of a person or animal in response to external or internal stimuli.
b. One of these actions or reactions: "a hormone ... known to directly control sex-specific reproductive and parenting behaviors in a wide variety of vertebrates" (Thomas Maugh II).
3. The manner in which something functions or operates: the faulty behavior of a computer program; the behavior of dying stars.

[Middle English behavour, from behaven, to behave (on the model of havour, behavior, from Old French avoir, from avoir, to have); see BEHAVE.]

be·havior·al adj.
be·havior·al·ly adv.

Synonyms: behavior, conduct, bearing, deportment, comportment, demeanor
These nouns all pertain to a person's actions as they constitute a means of evaluation by others. Behavior is the most general: The children were on their best behavior.
Conduct applies to actions considered from the standpoint of morality and ethics: "Life, not the parson, teaches conduct" (Oliver Wendell Holmes, Jr.)
Bearing often carries with it the implication of social standing or position: "It was evident from his bearing that he belonged to the country's ruling élite" (Amitav Ghosh).
Deportment and comportment pertain more narrowly to actions measured by a prevailing code of social behavior: "the alleged decline in standards of deportmenta significant issue for an institution that prided itself on turning out 'gentlemen'" (Jerome Karabel). "Would I see a different person, or merely the same one governed by different conventions of comportment ... accoutrement, and dress?" (Witold Rybczynski).
Demeanor suggests outward appearance that manifests inward emotion or character: "The Beth I saw now was not only nimble-footed, but her demeanor was exuberant and self-assured" (Rachel Simon).

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

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